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Author Topic: STOP: Numerical Instability  (Read 1550 times)

Amro Tohamy

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STOP: Numerical Instability
« on: September 16, 2017, 11:17:12 pm »

I have received this message (STOP: Numerical Instability) after performing 171.74 seconds from 300 seconds simulation time.
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Jared

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Re: STOP: Numerical Instability
« Reply #1 on: September 17, 2017, 03:54:51 pm »

This error occurs for a number of different reasons but basically means that the time that it took to complete each time step was too long and getting more out of control.  When this error happens, open up smokeview and load a plot3d file which is created by the numerical instability at the last time step of the simulation before the crash.  This should help you determine what went wrong so that you can adjust the model accordingly.
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MB

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Re: STOP: Numerical Instability
« Reply #2 on: October 11, 2017, 01:16:37 am »

is the pressure in the room too high?

I always make a small hole to allow air to flow.

The print can be checked by means of a corresponding SLICE.

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Stancil

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Re: STOP: Numerical Instability
« Reply #3 on: December 01, 2017, 02:33:18 am »

Is making a small hole like that really helpful? I would rather avoid doing that if I can.
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FireSert14

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Re: STOP: Numerical Instability
« Reply #4 on: December 18, 2017, 07:36:35 pm »

It depends where your issue lies, opening smokeview or the result spreadsheets should help find what the issue is before anything and where it happens. I know I've had pressure and velocity issues causing numerical instability before, the mesh setup is also really important and could be on of the parameters causing the instability so make sure they are setup properly (I think it usually is a result of a few different factors making the software crash, rather than a single one, except when the pressure is the big issue).
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